Here are some of Excel spreadsheets for use in CAD guitar drawing, setup, and general guitar-related geekery:

• fretcalc.xls - Your basic fret scale calculator.
• nb_radius_calc.xls - This is useful for seeing how well a given nut or bridge radius matches up with a fingerboard radius. For example, if you have a fixed 14″ radius Floyd Rose bridge and a 10″ radius neck it will tell you what shims are required on which saddles at the bridge to make them match.
• shimcalc.xls - This is used to calculate how much of a shim or angle is required in a flat bolt-on neck pocket to achieve a given action change at the bridge.
• string_layout.xls - This is a handy reference for drawing the strings and fingerboard perimeter on a CAD guitar model.
• tuner_layout.xls - This is used to figure out where to place tuners for straight string pull. Choose your string gauges, post diameter, etc. and it does the rest.